1. Field of the Invention
The present invention relates to systems and methods for remotely reporting the status of vending machines, and more particularly, to a remote vending machine monitoring and reporting system that provides reliable communication of data in DTMF code format between a vending machine and a remote central location.
2. Description of the Related Art
There have been numerous attempts over the years to develop effective monitoring systems for vending machines. Typically, these monitoring systems are designed to ascertain various occurrences within vending machines such as inventory changes, service calls, cash receipts, product purchases, and sold out conditions. However, the broad generic functions of current vending machine monitoring systems are limited in providing effective and inexpensive communication between a vending machine and a central reporting location.
For example, U.S. Pat. No. 4,412,292 to Sedam et al. discloses a system that automatically communicates vending machine conditions to a central computer complex. Each vending machine includes a microprocessor which monitors, stores and transmits data to the central computer complex either immediately or at scheduled call-in times. The distributed logic between the vending machine microprocessors and central computer complex provides various alarm function signals, inventory control support and route planning for the supply and maintenance of the machines. In a preferred embodiment, the data is transmitted between the central computer complex and each vending machine over telephone lines. The system, however, requires either substantial rewiring or numerous dedicated telephone lines.
U.S. Pat. No. 4,766,548 to L. A. Cedrone et al. discloses a microprocessor controlled system for monitoring, storing and periodically reporting data pertinent to the commercial operation of a vending machine to a central data collection and monitoring computer. The computer periodically reports such data over a telephone line accessed on a non-dedicated basis. Although this system has some advantages over the system disclosed in U.S. Pat. No. 4,412,292, it still requires telephone connections between the vending machines and central data collection center, undesirably tying up existing telephone lines.
U.S. Pat. No. 5,339,250 to M. J. Durbin discloses an interactive hotel vending network which includes a central control at the hotel main desk and a vending unit in each hotel guest room. The microprocessor controlled vending units include a display arrangement for displaying prices of articles to be vended and a user allocatable keyboard for use in article selection and final purchase form the vending unit. Each purchase is a cooperative action between the central control and vending unit, and is completed by a vending unit acknowledgment signal required before actual billing of a rendered article occurs. Since the vending units communicate over the master television distribution (MATV) of the hotel, the Durbin network is limited to facilities employing a MATV system.
U.S. Pat. No. 5,452,344 to Larson discloses an apparatus and method for transmitting and receiving data over an electric utility line that connects two or more vending machines. The apparatus includes frequency shift keying (FSK) transmit and receive protocol and variable width databit protocol to distinguish between actual data and corrupted information (i.e., noise) traveling over the electric utility line. A location unit collects the distinguished data and forwards the data to a central site via a regular telephone line. The Larson apparatus and method requires using multiple protocols in a complex FSK format to communicate over power lines. Moreover, the amount of noise experienced on the electric utility lines may affect the integrity of collected data.
U.S. Pat. No. 3,656,145 to Proops discloses vending units that send a modulated carrier frequency signal containing vending information via an electrical conductor (i.e., AC distribution conductor) upon activation by a purchaser. The pulse signals are then relayed to a modulator unit that feeds the signals through capacitors to an AC distribution conductor. The apparatus of Proops reports the cost of each item purchased but does not provide information relating to the depletion of a specific good in a specific location of the vending unit. For example, the Proops apparatus would not report the number of potato chips bags in a bin (e.g., "B2") remaining after each purchase. In addition, as with Larson, the noise experienced on the AC distribution conductor may affect the integrity of modulated carrier frequency transmissions.
U.S. Pat. No. 5,530,737 to Bartholomew et al. discloses a system and method for transmitting voice signals over AC power lines in a telephone extension system. Specifically, Bartholomew teaches bidirectionally transmitting voice and/or dial tones between base and extension units using dual-tone multiple frequency (DTMF) coding over power lines. In essence, Bartholomew et al. teach a digital messaging system that transmits unique and matching security keys between a base unit and extension unit to offer private and secure telephone usage. The system, however, appears limited to telephone extension systems and does not suggest adaptability to a vending machine environment.
It is, therefore, desirable to provide an effective vending status reporting system that sends vending status information over one or more existing AC power lines.
It is further desirable to provide a vending status reporting system that reports a plurality of information relating to vending status to a central location.
It is also desirable to provide a vending status reporting system using a transmission protocol that does not adversely affect the integrity of data transmitted between components over AC power lines.
Additional desires, features and advantages of the invention will be set forth in the following description, and will be apparent from the description or may be learned by practicing the invention.